Closure assembly with valve and method for its manufacturing

ABSTRACT

A closure assembly for a container includes a closure cap having an open ended body with a peripheral wall and a top wall provided with a dispensing passage which is defined by a collar arranged to the top wall. A self closing valve is arranged in the closure cap. The valve includes a slit central portion and a skirt extending downwardly from the central portion, which has an outwardly extending flange. The skirt is arranged in the collar and the flange is located below the collar and extends radially outwardly beyond it. On a lower surface of the top wall, a plurality of lips is formed outward from the collar. The lips are folded over the flange such that the latter is partly enveloped between the lips and the top wall so as to secure the valve in the closure cap.

BACKGROUND

1. Technical Field

The present invention relates to a closure assembly for a container forcontaining a substance, e.g. foodstuffs or cosmetic products, whichclosure assembly comprises:

-   -   a closure cap which can be attached or is attached to the        container, which closure cap has a body with a peripheral wall        and a top wall provided with a dispensing passage which is        defined by a tubular collar arranged to the top wall, which body        is open on the end opposite the top wall so as to be placed on        an upper portion of the container, and    -   a resilient self closing valve, which is arranged in the closure        cap for closing off the dispensing passage and which comprises a        central portion, which is provided with at least one through        slit which is closed and seals the inside of the container when        it is in an unloaded state, and which is deformable by pressure        from the inside of the container to a state in which the slit is        open so as to allow dispensing of a substance from the        container, said closing valve further comprising a skirt which        extends downwardly from the peripheral edge of the central        portion, and which on its lower end has an outwardly extending        flange,    -   wherein the skirt of the valve is arranged concentrically in the        collar of the cap and the flange of the valve is located below        the collar and extends radially outwardly beyond it.

2. Description of the Related Art

In EP 405 472 a closure for use on a squeeze type container isdescribed. The closure has a top wall with a collar extending upwardlyfrom it. In the closure assembly a self closing valve is arranged,comprising a convex dome shaped member which is positioned over theouter end of a dispensing passage defined by the collar and also overthe upper end face of the collar. The valve further comprises a skirtextending from the peripheral edge of the dome shaped member downwardlythrough the collar. On the opposite end of the skirt an outwardlyextending flange is formed which engages behind the lower end of thecollar thereby fixing the valve in the closure cap.

SUMMARY

An object of the invention is to provide an improved closure assembly.

This object is achieved by a closure assembly, wherein the flange of thevalve has a thickened portion, and, on a lower surface of the top wall,a round wall or a plurality of lips arranged in a round configurationare integrally formed at a distance coaxially and radially outward fromthe collar defining the dispensing passage, which cylindrical wall orlips are folded over at least a part of the flange such that the flangeis enveloped at least partly between the round wall or the lips and thetop wall so as to secure the valve in the closure cap.

The invention also relates to a method for manufacturing a closureassembly for a container for containing a substance, comprising thesteps of:

-   -   providing a closure cap which is to be attached to the        container, which closure cap has a body with a, preferably        substantially cylindrical, peripheral wall and a top wall        provided with a dispensing passage which is defined by a tubular        collar arranged to the top wall, which body is open on the end        opposite the top wall so as to be placed over an upper portion        of the container, and which cap has round, preferably        cylindrical, wall or lips arranged in a round configuration,        which are preferably shaped as cylinder segments, integrally        formed on the lower surface of the top wall and extending        therefrom coaxially with the dispensing passage;    -   arranging a covering lid on the upper side of the top wall        thereby covering the dispensing passage;    -   providing a resilient self closing valve comprising a central        portion provided with at least one through slit, and a skirt        which extends downwardly from the peripheral edge of the central        portion, and an outwardly extending flange which is provided at        the lower end of the skirt;    -   positioning the valve in the closure cap by inserting the        central portion and the skirt from below concentrically within        the cylindrical collar dispensing passage, and by positioning        the flange of the valve against the lower end of the collar; and    -   folding the round wall or lips over at least a part of the        flange thereby at least partly enveloping the flange between        said wall or said lips and the top wall so as to secure the        valve in the closure cap.

The fact that the round wall or lips are extending downwardly from thetop wall makes it possible to approach them from below with a suitabletool to bend them so as to secure the flange of the valve. This makes itpossible to bend the wall or lips with a lid positioned over the uppersurface of the top wall. Preferably, the closure cap and the lid areprovided by injection moulding them in one piece from a suitableplastic. The closure cap and the lid are then mutually connected by anintegral hinge or the like, which as such is known from the prior art.It is advantageous to have the hingedly connected lid in a closedposition with respect to the cap, because it provides an easier handlingof the closure cap during the assembly process, wherein the valve ismounted in the cap. In particular when the assembly takes placeautomatically, the closed lid allows for a simpler handling equipment toconvey and hold the cap during the assembly process.

Preferably the closure cap is positioned upside down when positioningthe valve in it, in which event the simple handling equipment comesforward even more.

The lips or cylindrical wall are bended by heating them and submitting amechanical bending pressure force to them by a forming surface of asuitable tool. Preferably the energy for heating the lips or thecylindrical wall is provided by ultrasonic waves which are directed intothem, preferably through the forming surface.

Preferably the valve is manufactured by injection moulding it from asilicone rubber. Preferably, the slit is provided in the central portionof the valve just before positioning the valve in the closure cap.

Preferably, at the upper end of the collar an inwardly extending radialflange is provided. This flange prevents dispensed substances or otherparticles from getting into the annular space between the skirt of thevalve and the inside of the collar, which could impede an outwardmovement of the skirt of the valve and thereby impede the opening of thevalve. Furthermore, in the event of foodstuffs, smearing of the spacebetween the skirt of the valve and the inside of the collar could causea hygiene risk.

Another aspect of the invention relates to a self closing valve made ofa resilient material, in particular silicone rubber, and comprising adome shaped central portion, which is provided with at least one throughslit and which is inwardly concave when it is in an unloaded state, inwhich unloaded state the slit is closed and seals the inside of thecontainer, and which dome shaped central portion is deformable bypressure from the inside of the container to a convex shape in which theslit is open so as to allow dispensing of a substance from thecontainer, said closing valve further comprising a skirt which extendsdownwardly from the peripheral edge of the central portion, and which onits lower end has an outwardly extending flange.

Such a valve is known from EP 160 336.

This aspect of the invention has for an object to provide a self closingvalve which has improved opening characteristics with respect to theknown valve.

This object is achieved by a valve according to the present principles,wherein at the transition between the dome shaped central portion andthe skirt an annular groove is present.

BRIEF DESCRIPTION OF DRAWINGS

The invention will be described in more detail in the followingdescription of preferred embodiments with reference to the drawings,wherein:

FIG. 1 shows a view in perspective of a closure cap of a closureassembly according to the invention with a hingedly connected coveringlid in an open position,

FIG. 2 shows the closure cap of FIG. 1 in a position upside down,

FIG. 3 shows a perspective view from above of a self closing valve of aclosure assembly according to the invention,

FIG. 4 shows a perspective view from below of the self closing valve ofFIG. 3,

FIG. 5 shows a cross section of the self closing valve of FIG. 3,

FIG. 6 shows a cross section of a preferred embodiment of a closureassembly according to the invention during assembly,

FIG. 7 shows a cross section of the closure assembly after the valve hasbeen secured in the closure cap,

FIG. 8 shows a cross section of another preferred embodiment of aclosure assembly according to the invention,

FIG. 9 shows a sectional view of a closure cap for a tube containeraccording to the invention,

FIG. 10 shows a view in perspective from below the closure cap of FIG.9,

FIG. 11 shows a view in perspective from above the closure cap of FIG.9,

FIG. 12 shows a sectional view of an upper part of a tube container withthe closure cap of FIG. 9,

FIG. 13 shows a view in perspective of another tube container with anintegral closure cap,

FIG. 14 shows a sectional view of the container of FIG. 13, and

FIG. 15 shows a sectional view of another embodiment of a self closingvalve of a closure assembly according to the invention.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

In FIGS. 1 and 2 a closure cap 1 is shown which is to be attached to acontainer, e.g., a squeeze type container for foodstuffs, like saucesas, e.g., ketchup, mayonnaise or mustard. Such containers usually have aneck for attaching a closure.

The closure cap 1 has a body 2 with a substantially cylindricalperipheral wall 3 and a top wall 4. The peripheral wall can also haveanother round shape. The top wall 4 is provided with a dispensingpassage 5 which is defined by a cylindrical collar 6 arranged to the topwall and extending upwardly therefrom. The body 2 is open on the endopposite the top wall 4 so as to be placed over an upper part of thecontainer. In general, the container will have a neck portion with anouter thread. Inside the peripheral wall 3, the closure cap 1 has acylindrical skirt 15 which extends from the top wall 4 downward andwhich on its inside is provided with a thread 16 for cooperating withthe outer thread on the neck of the container.

The top wall 4 is generally flat and has a conical central portion 4 a.The collar 6 is located in the centre of the conical portion 4 a. Thelower end 7 of the collar 6 extends beyond the lower surface 4 b of thetop wall 4 directly surrounding the collar 6, in this case thus theconical part 4 a, which is best seen in FIG. 6. In a practicalembodiment, the lower end 7 may extend 0.6 mm from the lower surface 4 bdirectly surrounding the collar 6.

In a preferred embodiment, which is shown in FIG. 8, the upper end ofthe collar 6 is provided with an inwardly extending radial flange 86.

A plurality of lips 8 shaped as cylinder segments are integrally formedat a distance coaxially and radially outward from the collar 6. The lips8 extend in an undeformed state, which is shown in FIGS. 2 and 6, inaxial direction beyond the flat part of the lower surface of the topwall 4 as can be seen in FIG. 6. The lips 8 surround the collar 6 suchthat between the lower end 7 of the collar 6 and the cylindrical wall orthe lips 8 an annular seat 10 is formed. Alternatively, a fullcylindrical wall instead of lips could be provided, which could bebended over the flange 24. However, the use of separate lips allows foreasier deformation as a closed cylindrical wall.

A covering lid 11 is hingedly connected to the closure cap 1 by means ofone or more a hinge members 12. The lid 11, the closure cap 1 and theone or more hinge members 12 are in the preferred embodiment mouldedintegrally from a plastics material, e.g., polypropylene. Although notpreferred at this moment, the lid and the closure cap could also beseparate components, which are assembled. The lid 11 is pivotable from aclosed position, which is shown in FIGS. 6 and 7 in cross section, whereit lies over the upper surface of the top wall 4 and the dispensingpassage 5, to an open position spaced away from the upper surface of thetop wall 4 and the dispensing passage 5, as is shown in FIGS. 1 and 2.

The lid 11 has on its lower side 13 an annular clamping sleeve 14 forengagement on the outside of the collar 6 in the closed position of thelid 11 as is shown in FIGS. 6 and 7. Alternatively, the lid 11 has aclamping sleeve 84 which engages on the inner end of the flange 86 ofthe collar 6, as can be seen in FIG. 8. Furthermore the lid 11 has astop member 17, in this case also with a cylindrical shape, protrudingfrom the lower side 13 of the cover 11.

A resilient self closing valve 20, which is shown in FIGS. 3-5, isarranged in the closure cap 1 so as to close off the dispensing passage5. The valve 20 is manufactured from a silicone rubber by injectionmoulding. The valve 20 comprises a dome shaped central portion 21, whichin this embodiment is provided with two intersecting through slits 22.Also, another number of slits is conceivable. The dome shaped centralportion 21 is inwardly concave when it is in an unloaded state, whichstate is shown in the figures. In this unloaded state the slits 22 areclosed and the valve 20 seals the dispensing passage 5. The dome shapedcentral portion 21 is deformable to a convex shape in which the slits 22are open. During opening of the valve the skirt moves at least partlyoutwardly. This deformation from the concave to the convex shape isinduced by a pressure increase in the inside of the container, e.g.,resulting from squeezing the container. A substance can then bedispensed from the container through the opened up slits 22. The closingvalve 20 further comprises a skirt 23 which extends downwardly from theperipheral edge of the central portion 21.

At the transition between the lower surface of the dome shaped centralportion 21 and the skirt 23, an annular groove 26 is present, therebyproviding a resilient circumferential connection between the dome shapedcentral portion 21 and the skirt 23 which allows the transition of thedome shaped member from a concave to a convex shape and vice versa.

On the lower end of the skirt 23 an outwardly extending circumferentialflange 24 is arranged. The flange 24 has is on its outer portion 25thickened with respect to the remainder of the flange 24.

In a preferred embodiment, the upper surface 21 a of the dome shapedcentral portion 21 has a constant radius of curvature as can be seen inthe cross sectional view of FIG. 5. The lower surface 21 b of the domeshaped central portion 21 has a flat central surface part 21 c and aconical outer surface part 21 d which surrounds the flat surface part 21c. The conical surface part 21 d is slightly curved seen in the crosssection of FIG. 5.

For the sake of clarity it is noted that the valve 20 is shown upsidedown in FIG. 5 and that in the figure the upper surface 21 a is facingdownwards and the lower surface is facing upwards.

The skirt 23 of the valve 20 has a relatively small thickness whereby itcan deform and move outwardly during opening of the valve. Preferably ithas a thickness of about 0.3 mm and a length in the range 3.5-5.5 mm,most preferably in the range 4-5 mm. The groove 26 between the skirt 23and the dome shaped central portion 21 of the valve 20 has a depth of0.4-1.2 mm measured from the outer edge of the conical surface part 21d.

In a particularly preferred embodiment of the valve 20 the skirt 23 hasa thickness of 0.3 mm, a length of 5 mm and the groove 26 has a depth of0.5 mm. In another particularly preferred embodiment of the valve 20 theskirt 23 has a thickness of 0.3 mm, a length of 4 mm, and the groove 26has a depth of 1 mm. Tests have shown that the latter embodiment opensup with a notably lower pressure than other embodiments. This isadvantageous if, e.g., a sauce with particles is to be dispensed and afilter effect where the particles remain in the valve 20 is reduced.

During assembly of the valve into the closure cap 1, the covering lid 11is in the closed position. The closure cap 1 is preferably positionedupside-down and resting on the top surface of the lid 11 as is shown inFIG. 6.

Next, the valve 20 is arranged in the closure cap 1 by inserting thedome shaped central portion 21 and the skirt 23 from the open ended sideof the body 2 concentrically within the cylindrical collar 6 and in thedispensing passage 5. There is a radial space between the outer surfaceof the skirt 23 and the inner surface of the collar 6.

The flange 24 of the valve 20 is located below the collar 6 and extendsin the radial outward direction beyond it. The flange 24 is positionedagainst the lower end 7 of the collar 6 and the thickened outer portion25 of the flange 24 is received in the seat 10 constituted between thelips 8 and the lower end 7 of the collar 6.

When the thickened portion 25 of the flange 24 of the valve 20 is in theseat 10, the circumferential edge of the slit central dome shapedportion 21 of the valve 20 is located at the same height as the upperedge of the collar 6 as can be seen in FIGS. 6 and 7. Alternatively, thecircumferential edge of the slit central dome shaped portion 21 of thevalve 20 is located against or just below the flange 86 at the upper endof the collar 6 as can be seen in FIG. 8. The dome shaped portion 21rests against or is just a small distance spaced from the end face ofthe stop member 17. In use, in the event that the lid 11 is in theclosed position as is the case in FIGS. 6 and 7, the stop member 17prevents the central dome shaped portion 21 of the valve 20 to deformoutwardly in case the inside of the container is pressurized. Thus, thevalve 20 is kept closed although the container is internallypressurized, thereby preventing spoiling of substance on the lid 11 andthe upper face of the top wall 4.

Next, the lips 8 are folded over the thickened portion 25 of the flange24 thereby enveloping the thickened portion 25 between the lips 8 andthe top wall 4 such that the valve 20 is secured in the closure cap 1.The lips 8 are folded by pressing a forming surface (not shown) againstthem while the plastics material is heated. The heating of the materialresults preferably from ultrasonic frequency vibrations which aredirected into the lips 8 via the forming surface. The ultrasonicfrequency vibrations are generated by a suitable generator therefore,which generators are known in the art. Heating could also be provided byother means, but heating by means of ultrasonic vibrations is preferred,because it allows for a considerably reduced heating time. When theplastics material is cooled again, the bent lips 8 hold the siliconerubber valve 20 securely in the seat 10. The thickened portion 25functions as a sealing ring within the seat 10 such that no fluidsubstance can flow beyond the valve 20 except for substance expelledthrough the open slits 22.

The lips 8 in the folded state as shown in FIGS. 7 and 8 are notextending beyond the level of the flat part 4 c of the top wall 4.Thereby, the possibility is created to arrange a foil 88 in the closurecap against the top wall. The foil 88 is an induction sealing foil whichafter the closure cap has been screwed onto the neck portion of thecontainer engages the top rim surrounding the dispensing opening of thecontainer. The sealing foil 88 can then be heated by induction heatingwhereby it is attached to said top rim and seals the dispensing openingof the container. The induction seal 88 protects the substance in thecontainer against quick degradation. The consumer, before dispensing thesubstance from the container for the first time has to remove thisinduction seal 88.

It is preferred to make the slits 22 in the central dome shaped portion21 of the valve 20 just before positioning the valve 20 in the closurecap 1. This has the advantage that between the moulding of the valve andthe actual arrangement of the valve 20 in the closure cap 1, the chancethat dust or other undesired dirt particles getting into the slits 22,which could contaminate foodstuffs flowing therethrough, is reduced.

In FIG. 15 an alternative embodiment of a self closing valve is shown.Parts of the self closing valve that correspond to the valve of FIGS.3-5 are indicated by the same reference numerals, provided with a prime(′).

A difference between the valve 20′ of FIG. 15 and the valve 20 of FIG. 5is that the valve of FIG. 5 has on its outer portion 25 a thickenedportion with a substantially circular cross section, whereas the valve20′ of FIG. 15 has an outer portion 25′ with a substantially rectangularshape. The outer portion 25′ is higher than the outer portion 25 ofvalve 20, which was found to allow a better fixation of the valve 20′ bythe lips 8 in the closure cap 1.

Another difference between the valve 20′ of FIG. 15 and the valve 20 ofFIG. 5 is that the skirt 23′ of the valve 20′ is less conical than theskirt 23 of the valve 20. Preferably the angle between the central axisof the valve 20′ and the skirt is about 1°, or in other words the angleα between the plane normal to the central axis of the valve is 89°. Theconical shape of the skirt 23, 23′ is advantageous for the relief of thevalve 20, 20′ from the mould. During the assembly process of a closurecap, the valves 20, 20′ are collected in a collection box or the likefrom which they are automatically picked one by one to be arranged in aclosure cap 1. It was found that the valves 20′ with a draft angle ofabout 1° have a smaller tendency to nest into each other when they arein the collection box. This results in less faults during the assemblyprocess, which is economically advantageous.

Another difference between the valve 20 of FIG. 5 and valve 20′ of FIG.15 is that the latter has a deeper groove 26′. The groove 26′ betweenthe skirt 23′ and the central portion 21 of the valve 20′ has a depth ofapproximately 1 mm measured from the outer edge of the conical part 21d′.

In FIGS. 9-12, another embodiment of a closure cap according to theinvention is illustrated. FIGS. 9-11 show a closure cap 101 which isadapted to be used for a tube container 120 (see FIG. 12). Such atubular container body 120 is typically manufactured by extrusion of atube from a suitable plastic material, e.g. polyethylene and cutting theextruded tube to length.

The closure cap 101 is preferably made by injection moulding from asuitable thermoplastic material, e.g. polypropylene or polyethylene, andhas a body 102 with a peripheral wall 103 and a top wall 104. The topwall 104 is provided with a dispensing passage 105 which is defined by atubular collar 106 arranged to the top wall 104. The body 102 is open onthe end opposite the top wall 104.

In the embodiment shown in FIGS. 9-12, the top wall 104 is generallyconical and with respect thereto has a central portion 104 a, which isin this example conical, in the centre of which the collar 106 islocated.

A plurality of lips 108 shaped as cylinder segments are integrallyformed at a distance coaxially and radially outward from the collar 106.The lips 108 extend in an undeformed state in axial direction. The lips108 surround the collar 106 such that between the lower end 107 of thecollar 106 and the cylindrical wall or the lips 108 an annular seat 110is formed.

A valve 20 is arranged in the closure cap 101 by inserting the centralportion 21 of the valve 20 and the skirt 23 from the open ended side ofthe body concentrically within the collar 106 in the dispensing passage105. The flange 24 of the valve 20 is positioned against the lower end107 of the collar 106. The lips 108 are folded over the thickenedportion 25 of the flange 24 thereby enveloping at least a part of theflange 24 between said lips 108 and the top wall 104 so as to secure thevalve 20 in the closure cap 101. The lips 108 are folded preferably byapplication of ultrasonic frequency vibrations as is describedhereabove.

The assembled closure cap 101 can be attached to a tubular containerbody 120 of a tube container. This is preferably done by laying an endportion of the tubular body 120 against the peripheral wall 103 of theclosure cap, in the shown example of FIG. 12 on the outer side. Next,said end portion of the container body is sealed to the peripheral wallby welding.

After the closure cap 101 and the tubular container body are attached toeach other, they can be conveyed to a filling machine where the tubecontainer is filled with a substance through the open rear end of thetubular body. Next, the rear end of the tubular body is closed bysealing, preferably by folding it and welding the end so as to close it.

According to the invention it is also possible to form a containerintegrally with a closure cap as will be described in the following withreference to FIGS. 13 and 14.

The container body 220 is manufactured with an integral closure cap 201of a suitable plastic material, e.g. polyethylene or polypropylene, byinjection moulding. The closure cap 201 has a body 202 with a peripheralwall 203 and a top wall 204. The top wall 204 is provided with adispensing passage 205, which is defined by a tubular collar 206arranged to the top wall 204. The closure cap 201 has lips 208 arrangedin a round configuration integrally formed on the lower surface of thetop wall 204 and extending therefrom coaxially with the dispensingpassage 205. In FIGS. 13 and 14 these lips are shown in an unfoldedstate. The top wall 204 is, in the example shown, generally flat andwith respect thereto has an inwardly extending central portion 204 a,which is preferably conical, in the centre of which the collar 206 islocated.

A resilient self closing valve 20 is positioned in the closure cap 201by inserting the central portion 21 and the skirt 23 from the open endedside of the body concentrically within the collar 206 in the dispensingpassage 205. The flange 24 of the valve 20 is positioned against thelower end 207 of the collar 206 and the outer portion 25 is placed inthe seat 210.

Next, the lips 208 are folded over the thickened portion 25 of theflange 24, preferably under application of ultrasonic vibrations asdescribed in the above. Thereby, at least a part of the flange isenveloped between said wall or said lips 208 and the top wall 204 so asto secure the valve 20 in the closure cap 201.

The container body 220 can be filled with a substance, e.g., a cosmeticproduct, after which the open rear end 221 is closed by e.g. pressing itflat and sealing it by adding heat. Alternatively a bottom part (notshown) can be attached to the rear end to close it.

The invention claimed is:
 1. A self-closing valve adapted to be arrangedin a closure of a container, said self-closing valve being made of aresilient material and comprising a dome shaped central portion having aperipheral surface and having in an unloaded state a concave outer sideand a convex inner side, wherein the surface at the concave outer sideof the dome shaped central portion has in the unloaded state a constantradius of curvature seen in cross section, and wherein the inner side ofthe central portion, has a flat central surface portion and a conicalouter surface portion which surrounds the flat surface portion, saiddome shaped central portion being provided with at least one throughslit, said slit being closed in said unloaded state, and said domeshaped central portion being deformable by pressure to a shape in whichthe slit is open, said self-closing valve further comprising a skirtwhich extends from the peripheral surface of the central portion in linewith said peripheral surface such that an outer surface of the skirt andsaid peripheral surface are flush, said skin having an outwardlyextending flange at an end remote from said peripheral surface of thecentral portion, wherein an annular groove is present at a transitionbetween said skirt and said conical surface portion, said grooveextending from an outer edge of the conical surface portion of the domeshaped central portion to the skirt.
 2. The self-closing valve accordingto claim 1, wherein the conical surface portion is curved seen in crosssection.
 3. The self-closing valve according to claim 1, wherein theskirt of the valve has a thickness of about 0.3 mm.
 4. The self-closingvalve according to claim 1, wherein the skirt has a length in the range3.5-5.5 mm.
 5. The self-closing valve according to claim 1, wherein thegroove between the skirt and the central portion of the valve has adepth of 0.4-1.2 mm measured from an outer edge of the conical surfaceportion.
 6. The self-closing valve according to claim 5, wherein thegroove between the skirt and the central portion of the valve has adepth of approximately 0.5 mm measured from the outer edge of theconical surface portion.
 7. The self-closing valve according to claim 6,wherein the groove between the skirt and the central portion of thevalve has a depth of approximately 1 mm measured from the outer edge ofthe conical surface portion.
 8. The self-closing valve according toclaim 1, wherein the skirt has a thickness of 0.3 mm, a length of 5 mmand the groove has a depth of 0.5 mm measured from an outer edge of theconical surface portion.
 9. The self-closing valve according to claim 1,wherein the skirt has a thickness of 0.3 mm, a length of 4 mm, and thegroove has a depth of 1 mm measured from an outer edge of the conicalsurface portion.
 10. The self-closing valve according to claim 1,wherein the skirt of the valve is conical with an angle between acentral axis of the valve and the skirt of about 1°.
 11. Theself-closing valve according to claim 1, wherein the outwardly extendingflange, has a thickened portion.